Ocean Landscape Carving

For reasons that I don’t understand (although I’m not ruling out stupidity) why when I place an ocean in a new level (landscape created first), the ocean does not carve the landscape. I’ve followed every tutorial that I could find, and follow along with my own level, their terrain is carved around the water and mine remains a landscape square. Does anyone have any suggestions on things that I must be overlooking. I’ve tried with 4.26, 4.27 and 5.02, but I always get the same results. Any ideas? Thanks

Did you enable ‘edit layers’ on the landscape?